1. Field of the Invention
The present invention relates generally to projected video image display systems. More particularly, the invention relates to a computer-based projected video system and method of providing interaction directly with a projected video image without the need for an active computer input device.
2. Description of the Prior Art
Projected video image display systems of the kind which use a computer for generating a video image and a projection device for projecting the computer-generated video image onto an enlarged screen are becoming popular for use in making presentations to a group of people in a small to medium size conference room environment. In such projected video display systems, it is desirable for a user standing next to the projection screen (located a distance away from the computer) to be able to enter information interactively into the computer for modifying or generating new images during the presentation.
The conventional way to provide interaction with a computer requires use of an "active" element or computer input device to provide cursor movement control. Examples of common computer input devices include absolute positioning devices, such as light pens and digitizing tablets; and also relative positioning devices, such as joy sticks, mouse devices, and track balls. Such active input devices, however, are usually too limiting for effective use in projected video image display systems. For example, absolute positioning devices, such as conventional light pens, require the user to interact directly with the video screen display of the monitor associated with the computer. This disrupts the spontaneity of the presentation as the user must repeatedly go back and forth between the computer monitor and the projection screen when the user desires to change the computer generated video image. In the case of relative positioning devices, such as track balls or mouse devices, the user must be skillful in manipulating the track ball or mouse in space. This can be awkward and usually requires use of both hands (i.e. one hand to hold the track ball or mouse pad in space and the other hand to manipulate the track ball or mouse to move the cursor). Such two handed operation also disrupts the natural flow of the presentation.
Projected video image display systems which use a hand held light pen for enabling a user to shine a high intensity light directly onto a projection screen bearing a computer generated image to provide auxiliary information to a computer are known from the prior art. In such prior art systems, an optical sensing device is used for detecting the high intensity light aimed at the projected image on the screen. Signal processing apparatus are used for discriminating the changes in reflected light on the projected images from the computer generated images in order to input information interactively into the computer. Exemplary systems are disclosed in U.S. Pat. No. 5,138,304, issued to Barry Bronson, and U.S. Pat. No. 5,181,015, issued to Roger L. Marshall et al.
A disadvantage with the above described known systems, however, is that the optical sensing device and related signal processing apparatus are typically of special purpose design and therefore expensive. Also, the requirement of the active input device, i.e. the light pen, is also disadvantageous as the light pen can be easily misplaced or dropped or damaged during a presentation or the batteries can die off.
It would be desirable to provide a more natural and unobtrusive way for enabling a user to interact with a computer of a projected video image display system in order to modify the projected image. It would also be desirable to provide a projected video image display system that does not require an active input device, such as a light pen, mouse device, track ball, etc., for inputting changes to a computer. In particular, it would be desirable to provide an interactive projected video image display system which would optically recognize a particular feature or a pattern created by the combination of the projected video image and an object introduced onto the projected image by the user in order to trigger a desired computer operation. Finally, it would also be desireable to provide such an interactive projected video display system which obviates the need for special use and expensive optical sensing components and related signal processing apparatus.